This invention relates to a waste water treating apparatus, and more specifically to a waste water treating apparatus of a built-up type.
The built-up type water treating apparatus itself is known. For example, Japanese Patent Publication No. 19786/74 discloses an apparatus including a rotary body which is made of generally circular plates positioned at intervals by spacers, each of the plates being a number of fan-shaped sheets disposed radially about a rotating shaft. This rotary body is disposed within a waste water treating tank, and the apparatus is operated by rotating the rotary body while it is dipped in waste water to a depth corresponding to about half of its height in the diametrical direction, and then treating the waste water by the action of aerobic microorganisms that grow adhering to the rotary body. The fan-shaped sheets which constitute the rotary body of this built-up type waste water treating apparatus are made of a synthetic resin foam, such as polystyrene foam, in order to permit good adhesion of the microorganisms and render the apparatus light in weight. A rotary body composed of a synthetic resin foam cannot retain sufficient strength unless its thickness is at least about 10 to 20 mm. Furthermore, a number of rotary bodies would have to be used to increase the total surface area of the rotary body and thereby increase the number of microorganisms which will adhere to it. Since the rotary bodies have a large thickness, the apparatus on the whole will become extremely large-sized. Furthermore, in this apparatus, many fan-shaped sheets are provided via spacers in the axial direction of the rotating shaft, and a bolt extends through the fan-shaped sheets and the spacers to form a bundle of the fan-shaped sheets. On the other hand, the bolt is secured to a brace mounted radially on the rotating shaft to fix the fan-shaped sheet bundle to the rotating shaft. Since the formation of a fan-shaped sheet bundle and its fixation to the rotating shaft are effected by a bolt, it is rather troublesome to build up the apparatus.
It is an object of this invention to provide a waste water treating apparatus which is free from the defects of the conventional built-up type waste water treating apparatus, and which is easy to build up, can be rendered small-sized, and has superior durability and an excellent ability to treat waste waters.